Bottom Line:
The APLR group had less angulation change in the anterior dentition, compared to the CLR group.By changing the tube angulation in the APLR, the intrusive force significantly increased in the distally tipped tube of group 3 patients and remarkably reduced the occlusal plane angle.Furthermore, changing the tube angulation will affect the amount of incisor intrusion, even in patients with similar palatal vault depth, without the need for additional TSADs.

Objective: To evaluate and compare the effects of two appliances on the en masse retraction of the anterior teeth anchored by temporary skeletal anchorage devices (TSADs).

Methods: The sample comprised 46 nongrowing hyperdivergent adult patients who planned to undergo upper first premolar extraction using lingual retractors. They were divided into three groups, based on the lingual appliance used: the C-lingual retractor (CLR) group (group 1, n = 16) and two antero-posterior lingual retractor (APLR) groups (n = 30, groups 2 and 3). The APLR group was divided by the posterior tube angulation; posterior tube parallel to the occlusal plane (group 2, n = 15) and distally tipped tube (group 3, n = 15). A retrospective clinical investigation of the skeletal, dental, and soft tissue relationships was performed using lateral cephalometric radiographs obtained pretreatment and post en masse retraction of the anterior teeth.

Results: All groups achieved significant incisor and canine retraction. The upper posterior teeth did not drift significantly during the retraction period. The APLR group had less angulation change in the anterior dentition, compared to the CLR group. By changing the tube angulation in the APLR, the intrusive force significantly increased in the distally tipped tube of group 3 patients and remarkably reduced the occlusal plane angle.

Conclusions: Compared to the CLR, the APLR provides better anterior torque control and canine tipping while achieving bodily translation. Furthermore, changing the tube angulation will affect the amount of incisor intrusion, even in patients with similar palatal vault depth, without the need for additional TSADs.

Figure 1: The occlusal diagrams and intraoral photos. A-C, The C-lingual retractor and D-F, the antero-posterior lingual retractor. A, No posterior orthodontic appliance is in place. B, Pretreatment and C, Post en masse retraction by the C-lingual retractor. D-F, The posterior teeth are splinted buccally and the guide bar and posterior tubes are in place. E, Pretreatment and F, Post en masse retraction by the antero-posterior lingual retractor.

Mentions:
Retraction of the anterior teeth as a lingually splinted unit with forces applied from the splint to a palatal TSAD has a biomechanical advantage. If the retraction lever arms are of the correct length, the force vector will pass through the center of resistance.23 A C-lingual retractor (CLR) splints the six maxillary anterior teeth and retracts them by using palatal TSADs without posterior bonding (Figure 1A-1C).4 This eliminates adverse effects in lingual bracket-archwire systems such as torque loss or distalization of the buccal teeth resulting from friction in the brackets and tubes.5678 However, other undesirable movements of the anterior segment can occur because the lingual splint is retracted by flexible traction modules.5 If the malocclusion requires intrusion of the anterior segment and retraction, additional TSADs would be required. As reported earlier, a CLR provides bodily translation of the anterior segment; however, the canines can sometimes tip excessively.57 To avoid these complications, the canine segmental wire has to be sectioned to allow individual control of the teeth.67

Figure 1: The occlusal diagrams and intraoral photos. A-C, The C-lingual retractor and D-F, the antero-posterior lingual retractor. A, No posterior orthodontic appliance is in place. B, Pretreatment and C, Post en masse retraction by the C-lingual retractor. D-F, The posterior teeth are splinted buccally and the guide bar and posterior tubes are in place. E, Pretreatment and F, Post en masse retraction by the antero-posterior lingual retractor.

Mentions:
Retraction of the anterior teeth as a lingually splinted unit with forces applied from the splint to a palatal TSAD has a biomechanical advantage. If the retraction lever arms are of the correct length, the force vector will pass through the center of resistance.23 A C-lingual retractor (CLR) splints the six maxillary anterior teeth and retracts them by using palatal TSADs without posterior bonding (Figure 1A-1C).4 This eliminates adverse effects in lingual bracket-archwire systems such as torque loss or distalization of the buccal teeth resulting from friction in the brackets and tubes.5678 However, other undesirable movements of the anterior segment can occur because the lingual splint is retracted by flexible traction modules.5 If the malocclusion requires intrusion of the anterior segment and retraction, additional TSADs would be required. As reported earlier, a CLR provides bodily translation of the anterior segment; however, the canines can sometimes tip excessively.57 To avoid these complications, the canine segmental wire has to be sectioned to allow individual control of the teeth.67

Bottom Line:
The APLR group had less angulation change in the anterior dentition, compared to the CLR group.By changing the tube angulation in the APLR, the intrusive force significantly increased in the distally tipped tube of group 3 patients and remarkably reduced the occlusal plane angle.Furthermore, changing the tube angulation will affect the amount of incisor intrusion, even in patients with similar palatal vault depth, without the need for additional TSADs.

Objective: To evaluate and compare the effects of two appliances on the en masse retraction of the anterior teeth anchored by temporary skeletal anchorage devices (TSADs).

Methods: The sample comprised 46 nongrowing hyperdivergent adult patients who planned to undergo upper first premolar extraction using lingual retractors. They were divided into three groups, based on the lingual appliance used: the C-lingual retractor (CLR) group (group 1, n = 16) and two antero-posterior lingual retractor (APLR) groups (n = 30, groups 2 and 3). The APLR group was divided by the posterior tube angulation; posterior tube parallel to the occlusal plane (group 2, n = 15) and distally tipped tube (group 3, n = 15). A retrospective clinical investigation of the skeletal, dental, and soft tissue relationships was performed using lateral cephalometric radiographs obtained pretreatment and post en masse retraction of the anterior teeth.

Results: All groups achieved significant incisor and canine retraction. The upper posterior teeth did not drift significantly during the retraction period. The APLR group had less angulation change in the anterior dentition, compared to the CLR group. By changing the tube angulation in the APLR, the intrusive force significantly increased in the distally tipped tube of group 3 patients and remarkably reduced the occlusal plane angle.

Conclusions: Compared to the CLR, the APLR provides better anterior torque control and canine tipping while achieving bodily translation. Furthermore, changing the tube angulation will affect the amount of incisor intrusion, even in patients with similar palatal vault depth, without the need for additional TSADs.